#define _CRT_SECURE_NO_WARNINGS	

#include<stdio.h>
#include<math.h>

double distance(double x1, double y1, double x2, double y2)
{
    double tmp1 = pow((x1 - x2), 2);
    double tmp2 = pow((y1 - y2), 2);
    return sqrt(tmp1 + tmp2);
}

int main()
{
    double x1, x2, x3, y1, y2, y3;
    scanf("%lf,%lf", &x1, &y1);
    scanf("%lf,%lf", &x2, &y2);
    scanf("%lf,%lf", &x3, &y3);
    double d1 = distance(x1, y1, x2, y2);
    double d2 = distance(x1, y1, x3, y3);
    double d3 = distance(x3, y3, x2, y2);
    double p = (d1 + d2 + d3) / 2;
    printf("%.2lf", sqrt(p * (p - d1) * (p - d2) * (p - d3)));
    return 0;
}